1. Field of the Invention
The present invention relates to devices for protecting an integrated circuit against external attacks.
2. Discussion of the Related Art
It may be desirable to protect an integrated circuit against external attacks aiming, for example, at disturbing or even hindering the normal operation of the integrated circuit. An example of attack comprises scanning the front surface or the rear surface of the integrated circuit with a laser, especially a pulse laser. Such a method can enable to modify data stored in memories of the integrated circuit or to modify the logic states or the durations of signals transmitted along conductive tracks of the integrated circuit.
The integrated circuit may comprise a protection device which enables detecting that a laser attack is occurring. The protection device may then control the stopping of the integrated circuit, the deleting of confidential data, etc.
By way of example, the device of protection against laser attacks may comprise several electronic components, for example, photodiodes, memory elements of flip-flop type, formed in the integrated circuit. These components are sensitive to the light beam of the laser and behave as sensors allowing the presence of the laser beam to be detected.
However, such a protection device only enables detection a laser attack if the laser beam directly reaches one of the sensors of the protection device. To ensure a high probability of detection of an attack during a laser scan across an entire region of an integrated circuit, it is necessary to provide a large number of sensors. This necessitates an increase in the surface area of the integrated circuit dedicated to the protection device and thus in the integrated circuit manufacturing cost.